Molecular quantity analysis is widely used in research, diagnosis, quality control and other types of measurements. It is well known that the diagnosis and treatment of certain medical conditions can be facilitated by identifying the presence and quantity of a selected biomarker in a sample taken from a patient. Furthermore, research has shown that, in many situations, multi-biomarker measurements can provide a more accurate diagnostic result. More particularly, biomarker research has identified many helpful proteomics and genomic panels for disease diagnosis and prognosis, including cancer, infection, cardiovascular disease, diabetes, Alzheimer's disease and others. For example, a four-biomarker panel has been developed for detecting early stage ovarian cancer, and an 18-protein biomarker panel has been developed for the diagnosis of early Alzheimer's disease.
Current methods for protein-based biomarker assays typically utilize an enzyme-linked immunosorbent assay (ELISA) approach, where the target protein binds to a specific recognition molecule, and then colorimetric, fluorescent, electrochemical or magnetic signals are introduced to transduce the binding event into a readout signal. However, inasmuch as advanced instrumentation is typically required for quantitative detection of the target protein, these methods are not ideal for point of care applications, due to the size and high cost of the instrumentation and/or the complicated operation of the instrumentation. See, for example, FIG. 1, which shows the typical approach for a protein-based biomarker assay, where a blood sample is drawn from a patient and then processed by a relatively large, complex instrument.
Thus there is a need for a new method and apparatus for point of care determination of the quantity of a protein (and, preferably, the quantity of multiple proteins) present in a sample.